Burst orientation and botlane diversity don't correlate directly. The main reason for the current botlane meta is the fact that games are too snowball-heavy, conventional adcs are not given the time to scale up and the class they counter the most (tanks) were banished from the game due to conqueror.
Bruisers and mages in botlane are not nessecarily unhealthy for the game/ sign of an unhealthy burst meta. If conqueror gets nerfed / tank items buffed, so that tanks can return to the game. And some of the snowball mechanics are decreased, there can be a meta, where traditional adcs are equally viable as the bruiser/mage-botlanes.
You would draft an early game teamcomp with bruisers and mages in bot, that gets heavily punished if you don't manage to finish the game fast (which would ofc be harder than it is now), because of this comp being extremly bad at dealing with tanks and additionally facing the strenght of the scaling crit-build.
Yes such a meta has not been there yet, (so your initial statment is true up to date), but it doesn't have to always be true. I would be quite excited for such a meta, because there would be a lot of strategic variety, probably more than ever before.